Patent GB-190511537-A (GB)
Title: Improvements in and relating to Electric Motor Control Systems.
Filed: 1905-06-02
Granted: 1906-06-02
Abstract: 11,537. British Thomson-Houston Co., [General Electric Co.]. June 2. Switches.-In an electro-pneumatic master-control system for electric train motors, air is admitted alternately and with varying pressure from two train-pipes to pneumatically-actuated reversing, series, and parallel switches, and, when the desired connexions have thus been made, resistance is cut-out automatically by a series of separate electro-magnetic contactors. An overload cut-out is tripped electro-magnetically, although the pneumatic closing-gear still remains in position. Air is first admitted to either of the train-pipes 1, 2 at the lower pressure by turning the disk valve c<1> and the two-way cock v to suitable positions. In the valve v<1> the ports 42 lead to exhaust, the port 43 to reduced pressure supply, the ports 45, 49 to full pressure supply, and the ports 47 also to reduced pressure. A similar master-valve is placed at the other end of the car. If air is first admitted to the train-pipe 2, it passes through the pipes 6, 19 and depresses the piston 16, setting the reversing-switch RS as shown. If the pipe 1 is first supplied, the reverse connexions will be made. The fall of the piston 16 opens the valves 21, 22. The slide valve 25 is raised, forming a path through the pipes 1, 5, 26 ready for subsequent operations, and air is allowed to pass through the pipes 27, 28, closing line switches L, L<1>, L<2> and through the pipe 29 closing the series switch S. The series switch carries a number of auxiliary contacts s ... s<3> lying in the actuating and maintaining circuits of electro-magnetic resistance contactors R ... R<6>. These are themselves arranged with auxiliary contacts i .. i<4>, so that the closing of the first contactor R establishes a maintaining- circuit through its own cuil and diverts the actuating-current through the coil of the next contactor R<1>, the same operation being automatically repeated until all resistance is cut out. After the first contactor R has closed, the remaining ones close in pairs, R<1> simultaneously with R<4>, and so on. When the series switch S has closed, the actuating-circuit through the switch E, contact s, and coil i still remains open at 32. The latter gap is bridged on increase of the air pressure, which depresses the piston of the accelerating-relay' 30. The resistances r ... r<6> are then cut out, undue acceleration being prevented by means of a throttling-relay O. The last resistance contactors complete circuit through a bridging-switch' B, forming an additional direct path between the motors, and at the same time actuating an interlocked valve b, which exhausts the actuator of the series switch S and causes it to open. All the actuating and maintaining circuits of the resistance contactors are then broken, causing full resistance to be reinserted, but a maintaining-circuit for the switch B is established through s<3>. To put the motors in parallel, the pressure is first reduced, opening the accelerating-relay ' 30, and then air is admitted to the train-pipe 1, which follows the previously-prepared path to the pneumatic switch 38, depresses the piston, and closes an actuating- circuit through the coils of the parallel switches P. The interlocked valve p opens another exhaust path for the series-switch actuator, so that the latter is not affected by the closing of the exhaust through the valve b consequent upon the opening of the switch B. On the air pressure being raised, the ' accelerating-relay ' 30 is closed, as before, and an actuating-circuit for the resistance contactors is established through auxiliary contacts carried by the parallel switches. Resistance is then automatically cut out, as before. A circuit-breaker CB is placed in the path of the power current. It is normally held closed against a spring or the like by air from either train-pipe, but only if the toggle-link 11 has been previously latched to the piston-rod 10 by momentarily closing a handswitch D, which has the effect of energizing a magnet 14, partially straightening the toggle, and bringing the end 12 into engagement with the latch. An overload coil 15 trips the latch when necessary, and, since the magnet 14 is not strong enough alone to hold the toggle compressed in the closed position, the lever 7 opens. To close the circuit-breaker, the train-pipes must be exhausted, the motor controllers brought to their ' off' positions, and the switch D again momentarily closed.